1. Field of the Invention
The present invention is directed to the field of microelectronics, and more particularly, to heat dissipation in microelectronics.
2. Description of Related Art
Currently, demand for higher performing microprocessing devices is resulting in microelectronic components having increasing levels of power density and heat dissipation. As the reliability and lifespan of a microelectronic component is dependent on the operating temperature, removal of heat from microelectronic components has become one of the most important issues facing computer systems designers today.
Conventional thermal control schemes, such as heat sinks, air cooling with fans, thermoelectric cooling, heat pipes, and vapor chambers have either reached their practical application limit or are soon to become impractical for recently emerged microelectronic components. Current heat dissipation of values of 20 W to 50 W are estimated to increase to 100 W and even 200 W in the next five to ten years. Thus, the reliability of these microelectronic component systems will suffer if high temperatures are permitted to exist.
In an attempt to address the need for greater heat dissipation, one prior art technique utilized a microelectromechanical system (MEMS)-based-micro-channel cooling system embedded in the substrate of the microelectronic component as further described herein with reference to FIG. 1. FIG. 1 illustrates a functional diagram of an integrated circuit (IC) chip package 100 including a voltage-controlled, electrokinetic (EK) microcooler system 110 embedded in a substrate 114 on which an IC 112 is formed. EK microcooler system 110 removed dissipated heat from integrated circuit (IC) 112 utilizing a two-phase cooling loop having an electrokinetic (EK) pump 116.
In this prior art technique, liquid was circulated under high pressure (for example, 5 atm) in a closed loop at least part of which was in thermal contact with underlying IC 112. Heat exchangers, such as microchannels or microjets, transferred heat from IC 112 to an evaporator region 120 of the closed loop above IC 112 by thermally conductive contact with evaporator region 120. An example of a microchannel heat exchanger is described in U.S. Pat. No. 4,573,067 to Tuckerman et al. entitled xe2x80x9cMethod and Means for Improved Heat Removal in Compact Semiconductor Integrated Circuitsxe2x80x9d and hereby incorporated by reference in its entirety.
The circulated liquid absorbed the heat and evaporated in evaporator region 120. The vapor then traveled through the closed loop to a condenser region 118 of the closed loop that was lower in temperature than evaporator region 120. The vapor then condensed to liquid releasing the heat. The liquid was then pumped back to evaporator region 120 by EK pump 116 and the cooling cycle repeated.
Advantageously, EK microcooler system 110 had no solid moving parts and was implemented as part of the fabrication process of substrate 114 of IC 112, and was therefore expected to be more compact and reliable. The high liquid pressure enabled two-phase micro heat exchangers for greater heat dissipation, utilized very small amounts of voltage to control EK pump 116 and, therefore, had reduced power consumption.
Unfortunately, MEMS-based micro-channel heat exchanger systems that were embedded in the substrate of a central processor unit (CPU) or an application specific integrate circuit (ASIC) using the fabrication process for cooling of microelectronic components had thermal inertia, heat removal inefficiency and very large heat rejection to heat absorption areas. Consequently, these systems provided little more heat dissipation than earlier, less costly heat dissipation techniques preventing their widespread application in the electronic industry.
According to the invention, a refrigeration cooling assisted MEMS-based micro-channel cooling system removes high heat densities by direct spot-cooling of electronic components using a primary cooling system thermally coupled with a secondary chip embedded cooling system. The invention maintains low levels of energy consumption with acceptable component sizes. The invention provides highly efficient chip embedded cooling with continuous or intermittent operation of the primary cooling system.
In one embodiment, the refrigeration cooling assisted MEMS-based micro-channel cooling system includes: a primary cooling system, such as a multiple compressor refrigeration heat sink module; at least one integrated circuit (IC) chip embedded secondary cooling system, such as a MEMS-based micro-channel cooling system; and at least one socket thermally coupling the primary and secondary cooling systems.
In one embodiment, a portion of an evaporator line from the primary cooling system is extended to the socket and is positioned in thermally conductive contact with the socket. When the IC chip embedded secondary cooling system is positioned in thermally conductive contact with the socket, heat generated by the integrated circuit is initially removed by the IC chip embedded secondary cooling system, and dissipated into the socket. The heat is then transferred from the socket to the evaporator line. The evaporator line, e.g., refrigerant circulating within the evaporator line, transfers the dissipated heat away from the socket to the primary cooling system for further dissipation.
By continually, or intermittently, removing heat transferred from the IC chip embedded secondary cooling system through the socket to the primary cooling system, the thermal inertia and heat rejection areas experienced in the prior art MEMS-based micro-channel cooling systems are significantly reduced allowing for higher heat dissipation levels.
It is to be understood that both the foregoing general description and following detailed description are intended only to exemplify and explain the invention as claimed.